The present invention relates to a sealing boot of a joint, and more especially relates to a constant velocity joint of a drive shaft or the like of a vehicle.
In general such a sealing boot may be mounted on an objective rigid structure, for instance on a rigid body having circular cross-section or a generally convex shaped curved cross-section by means of a securing band or the like by fastening from the outside thereof.
FIGS. 1 and 2 show one example of the sealing boot of a conventional type equipped on a constant velocity joint. In this example, there are formed three concave portions at the outer periphery of the objective rigid structure, or the housing under an object to decrease the overall weight or others.
FIGS. 1 and 2 show a tri-board type and sliding type constant velocity joint. In the figures, reference numeral 1 designates a housing formed integrally with a first shaft 2 at its end portion. This first shaft 2 is to be coupled with another second shaft 4. A spider 3 is formed integrally with said second shaft 4 at its end portion. Three spider shafts 5 are provided on the spider 3 to extend radially and each spaced apart at a 120.degree. angle from others on the periphery of the spider 3. A roller 6 is provided on each one of the spider shafts 5 about a needle 7 in a manner freely rotatable and slidable thereon. Three grooves 8 are provided on the housing 1 at a location of 120.degree. angle separation to extend in an axial direction and to support the rollers 6 to freely rotate therein. A cover 9 is arranged to fit on the outer circumference of the housing 1. Sealing boot 10 is arranged to cover the second shaft 4 and the joint. Both mounting portions 10a and 10b at the ends of the sealing boot 10 are fixed by respective fastening bands 11 and 12 on the cover 9 and the second shaft 4 respectively.
The mounting portions 10a and 10b of the sealing boot are generally made to have thick walls and a shape to fit the outer contour of the objective rigid structure and to have a small clearance therebetween to allow easy mounting and are fastened thereto by the fastening means. If the objective structure, such as the cover 9, is circular shaped, the fastening force of the fastening band may distribute uniformly among the outer wall of the boot and a complete sealing can be obtained. However, when the concave portions or the grooves are formed on the outer periphery of the housing 1 for reducing the weight and hence the cost or for other purposes as shown in FIG. 2, the cover 9 is of irregular shape to match the outer shape of the joint. In such a case, generally the cover 9 has a non-uniform shape due to the machining tolerance and especially because it has non-uniform surface finishing. Under such condition, a disadvantage appears in that the sealing boot 10 may not suitably fit onto the cover 9 in the circumferential direction at a connecting portion between the convex portion 1a and the concave portion 1b of the cover 9, namely at the edge portions 1c of the concave portion 1b. By the insufficient close fitting of the boot 10 against the cover 9, a desired complete sealing cannot be obtaned.